Numerous inquiries regarding details as to methods followed publication of our previous papers1 and are the reason for this somewhat elementary article. Practically all is in answer to questions that have been asked, some of them many times.

First of all, we wish to correct an error resulting from oversight: "Neutral acriflavine" should read "acriflavine," as acriflavine was used in all the tests reported.

A 5 per cent acriflavine solution is used because we have found this the weakest percentage that can be relied on to kill many resistant, spore-forming bacteria. Fifty per cent alcohol is used as a solvent because acriflavine is only slightly soluble in stronger percentages of alcohol; moreover, histologic experience shows that weak solutions of alcohol penetrate best, and this probably accounts for the well known fact that weaker percentages of alcohol have greater antiseptic value. Acetone is added because it apparently